The present invention relates to a method of producing and guiding intensive, large-area ion, electron and X-ray beams, with the guidance of the beam being effected already in the beam generator by means of operationally variable magnetic and electric fields and variable magnetic correction fields.
Such particle and X-ray beams with selectable beam characteristics are required, for example, for processing materials employed in the surface and thin-film technology and for beam induced lithographic processing, e.g. X-ray lithography. Another field of application is the examination of physical processes taking place in highly densified matter formed by intensive radiation at high energy density.
High intensity particle streams can be generated by means of ion diodes which are supplied with energy by powerful current sources which are available in the art. A type of diode is known in which a self-generated B.sub..theta. field is used to magnetically isolate the electrons in the diode gap. Ion currents up to 750 kA have been generated with such socalled B.sub..theta. diodes. You can find a description of a so called B.sub..theta. diode in: K. W. Zieher, Nuclear Instruments and Methods in Physics Research 228 (1984) 161-168.
Other Diodes of a type other than the B.sub..theta. diode are also known which have a comparable ion current yield but which, in their manner of operating, exhibit marked drawbacks compared to the B.sub..theta. type. They lack the clear electrode structure which distinguishes the B.sub..theta. diode and with which the physical processes can be clarified and influenced fairly well. A significant feature of such diodes is the development of nonstationary electrodes which are formed by variable space charge configurations. Thus, it is hardly possible to determine local acceleration and guidance fields or even calculate them. This applies, in particular, for the unstable, so-called virtual cathodes which do not permit clear beam focusing. Additionally, the degree of damage to parts of the diode structure by the free charge carriers of the diode plasma and by currents of free, not metallically bound electrons is so high that the diode is destroyed after a very short period of time (fractions of microseconds). Generally, the representatives of such plasma diode types (pinch diodes, pinch reflex diodes, etc.) survive only one short bombardment pulse. Then they must be regenerated or replaced completely.
Although the time for which a B.sub..theta. diode can be subjected to loads is much higher than for other diode types, the B.sub..theta. diode also requires the exchange of operationally important components after an effective period of operation of a few microseconds and its operation is by no means continuous. The reason for this is the high currents of free electrons which pass through the cathode/anode gap over paths of different lengths and destroy the anode supports they encounter while damaging parts of the anode surface upon impact. Another decisive drawback of all prior art high current diodes, including the B.sub..theta. diode, is that it is impossible to set and optimize the fields which influence the particle beam and which are determined by structure and geometric data. Thus, it is impossible to clearly guide a beam having the desired focusing characteristics.
These described drawbacks, namely the completely insufficient loadability time and the impossibility of a positive, clear beam guidance, make the prior art methods and arrangements unsuitable for industrially usable beam operation.